Graphite molds are used in the casting of steel particularly of steel slabs. Such mold structure generally includes a pair of spaced graphite side blocks and end, top and bottom blocks which are arranged to form a cavity of rectilinear cross section. Molten steel is poured into the cavity and solidified therein. The blocks are separated after solidification of the steel and the slab is removed.
Continual and repetitive use of the graphite blocks requires machining of the mold faces to maintain the desired surface characteristics of the cast slab. This machining gradually reduces the thickness of the mold side blocks. The thickness reduction causes the temperature of the graphite blocks to increase more rapidly.
This temperature increase is undesirable because the residual heat remaining in the graphite blocks increases the cooling or solidification times of subsequent castings. In fact it is essential that heat be removed from the blocks in order that the optimum solidification occur during subsequent castings.
One such method of cooling the graphite molds is described in U.S. Pat. No. 3,590,904 dated July 6, 1971. The method comprises generally the application of a water spray in heigthwise extending and laterally spaced passages or bores formed in the graphite blocks. While this method has been generally effective it has been demonstrated that a temperature gradient occurs along the length of each of the passages with a gradual increase occurring as the spray is applied further from the source of the liquid coolant. The temperature difference along the height or length of the passages is further implemented upon repetitive use of the blocks without sufficient time between castings to allow the high temperature to drop to the lowermost temperature along the passage.